Electronic control circuit elements used in conjunction with different types of motors are often packaged in close proximity to component parts of such motors such as the motor stator and rotor. In many cases, such elements are essentially enclosed within a housing of one type or another, and heat generated by one or more of such elements may contribute to ambient temperatures in the vicinity of various ones of the circuit elements such that malfunction or premature failure of an element may occur.
In the specific case of electronic controls used in brushless DC motors as depicted, for example, in the patent applications and patents incorporated by reference hereinabove; the circuit elements thereof include power switches (e.g., transistors), fuses, and other semi-conductor components which are susceptible to current surges. Normally, a surge suppressing resistor has also been used in the control to reduce the peak of such surge so that premature failure of various circuit elements, including those herein mentioned as being surge susceptible, does not occur.
As a point of reference, such a surge suppressing resistor is shown, in all of the above incorporated by reference Bitting and Bitting et al applications, as a three ohm resistor R22 in FIG. 2 of such application drawings. The above incorporated by reference Peil application also illustrates the use of such a surge suppressing resistor in the form of a five ohm resistor denoted by the reference numeral 25 in FIG. 1 of the Peil application drawings.
While the use of surge suppressing resistors diminish the negative effects of current surges, such resistors significantly contribute to the undesirable elevated ambient temperature problem for components mounted on the control circuit board with a surge resistor.
While it would be desirable to avoid the heating effect of surge suppressing resistors, heretofore there has been no apparent possibility of eliminating such resistors from the control circuits. For example, in the case of a ceiling fan application with a wall control as disclosed in the above-referenced Peil application, the triac action in the wall control creates current surges, the peak of which is four times the average current. Surges of this magnitude are not only harmful to transistors, diodes, and so forth, but also can cause fatigue in circuit board located fuses and cause premature fuse failure. For this reason also, surge suppression becomes essential.
It should now be understood that it would be desirable to provide methods of suppressing current surges in electronic motor control circuit components without significantly contributing to increased heating of the control circuit board or other environment surrounding such components. It would also be desirable to provide current surge suppressing means that protect circuit board mounted components without having a heating effect on such board and its ambient. Furthermore, it would be desirable to provide an improved combination of an electric motor and its associated electronic circuitry such that problems associated with circuit element heating are overcome.
Accordingly, it is a general object of the present invention to provide solutions to the problems mentioned above.
It is a specific object of the present invention to provide improved methods of operating electronically controlled motors that involve suppressing current surges in an electronic motor control circuit while dissipating heat associated with such suppressing procedure at a location remote from the circuit board that carries the circuit elements being surge protected.
It is another object of the present invention to provide current surge suppressing means for protecting circuit board mounted electronic motor control components without directly heating the protected components with the suppressing means.
A more specific object of the present invention is to provide an improved combination of an electric motor and electric circuitry associated therewith in order to overcome heating problems associated with such circuitry.